A. Field of the Invention
The present invention relates generally to the field of inflammatory diseases of the peripheral nervous system. More particularly, it concerns methods for treating inflammatory diseases of the peripheral nervous system by modulating sphingosine-1-phosphate receptor activity.
B. Description of Related Art
The peripheral nervous system (PNS) is a common target of immune attack. Chronic inflammatory demyelinating polyneuropathy (CIDP) is sometimes referred to as the PNS counterpart of multiple sclerosis (MS), which affects the central nervous system, due to similarities between the two diseases in terms of course of illness (relapsing vs. progressive), presence of focal demyelination and varying degree of axonal loss, and immune-mediated pathophysiology. Inflammatory infiltrates in CIDP nerves consist primarily of T cells and macrophages, suggesting that T-cell mediated reaction towards myelin antigens is a probable cause of tissue damage in CIDP. Available therapies for CIDP, such as intravenous gammaglobulin, plasmapheresis and steroids, are effective in two-thirds of patients, but are associated with complications or failure to induce a long-lasting remission (Ropper, 2003). Therefore, there is a pressing need to develop new therapeutic methods and agents that can be used alone or in combination with existing treatment modalities.